Objective To investigate the expression pattern and clinical significance of chromatin remodeling AT-rich interactive domain 1A (ARID1A) protein in gastric cancer and paired adjacent noncancerous tissue samples. Methods The expression of ARID1A protein was examined in 90 gastric cancer tissue samples and 90 paired adjacent noncancerous tissue samples by immunohistochemistry. The relationship of ARID1A protein expression with clinical-pathological characteristics was evaluated by Mann-Whitney test and Spearman correlation analysis. The relationship with clinical prognosis was analyzed by Kaplan-Meier survival curve, Log-Rank test and Cox regression model. Results ARID1A was expressed in both cytoplasm and nucleus of adjacent noncancerous tissues and gastric cancer tissues. Both cytoplasmic and nuclear ARID1A expressions significantly decreased in gastric cancer tissues compared with adjacent noncancerous tissues. Cytoplasmic ARID1A expression in adjacent noncancerous tissues was negatively correlated with clinical TNM stage. Meanwhile, nuclear ARID1A expression in adjacent noncancerous tissues was positively correlated with patients' age and negatively correlated with tumor size. Survival analysis showed that cytoplasmic ARID1A expression in adjacent noncancerous tissues was related with overall survival but not significantly, and that both cytoplasmic and nuclear ARID1A expressions in gastric cancer tissues were not related with clinical-pathological characteristics and prognosis. Conclusion ARID1A may play an important role in the early events of gastric carcinogenesis, and it can serve as a potential biomarker for early diagnosis.